Diazotype layers containing resorcinol derivatives



Patented Jan. 2, 1951 umrsn STATES TENT .t'l ECE DIAZOTYPE LAYERS CONTAINING RESOR- CINOL DERIVATIVES William H. von Glahn, Loudonville, and Lester N. Stanley, Delmar, N. Y., assignors to General Aniline & Film Corporation, New York, N. Y., a

corporation of Delaware No Drawing. Application January 20, 1948, Serial No. 3,326

8 Claims.

i copied, it is of particular advantage in many cases to first make an intermediate print or transition print on a transparent diazotype copying material by exposing a transparent sensitized diazotype material to actinic rays by either the printing-through or reflex process and then developing the diazotype material. The image thus produced on the intermediate or transition diazotype print can then be used for the reproduction of further diazotype prints in the usual manner, of high contrast. This method is particularly useful when it is desired to make a number of reproductions from a frail or valuable original which would be adversely affected, if not destroyed, in the repeated exposures necessary to make a large number of copies.

The efliciency of the process involving the production of a transition or intermediate print depends upon the opacity of the azo dye image produced upon such intermediate or such transition print to ultraviolet light and upon the transparency of the background portions thereof. It depends also upon the visual densi y of the image produced on the intermediate or transition print, since images of poor visual density, such as yellow on a white or transparent background, while having the desired degree of opacity to ultraviolet light, nevertheless, have the disadvantage of rendering difficult the detection of flaws in the intermediate image, and it is often necessary to make a contrasting print from the transition print before such flaws can be detected.

Prints of a deep color having a good visual density can be obtained from diazotypes including such azo components as phloroglucinol, but despite the density of the color constituting the image, its actinic opacity or photographic densityis insufiicient to reproduce the image satisfactorily in diazotype copies made therefrom. The azo coupling component used for the production of such images on prints which are to be used as intermediate or transition copies must be such as to produce, upon coupling with the diazc compound employed, a yellow to brown azo dye which will sufiiciently absorb ultraviolet light to prevent decomposition by light of the diazo compound in the areas to be reproduced from the intermediate 9; transition copies,

Coupling components such as resorcinol have been employed heretofore in diazotype transition.

print light sensitive layers for the production of color images having the desired light absorption characteristics for transition printing. While resorcinol will produce'the image on the transition print in azo dye colorations having good opacity to ultraviolet light and having sufficient visual density to assure detection of printing flaws, the pro-coupling stability of the diazotype layer is not sufficient to permit prolonged storage before use. It has been found that carriers, such as transparentized paper or film, having thereon a light sensitive layer composed of the usual diazo components and resorcinol gradually develop a discoloration prior to use, which discoloration is produced by premature coupling of the resorcinol and the diazo component. This discoloration will, of course, be retained by the transition print and impairs the capacity of the background areas to transmit actinic light. Consequently, the light sensitive diazo components in the diazotype media employed for copying from the transition print will not be efficiently decomposed in the background areas. This same discoloration, therefore, will be reproduced in the final copies, diminishing the contrast between the background and the image.

In addition, the colorations produced with res-l orcinol are in many cases not fast to light, and tend to fade over a period of time, particularly when exposed to prolonged or repeated actinic radiation used in making final copies from the transition prints. Furthermore, colorations thus produced often tend to offset; for example, they rub off when the transition copy is passed over hot rollers in the printing machine. When resorcinol is employed for the development of onecomponent diazotype layers, wherein the coupling component is applied in an aqueous developing solution to the previously exposed diazotype material, or when a two-component layer con-- taining resorcinol as the coupling component is developed by a wet or semi-wet process inwhich an aqueous alkaline solution is applied to the exposed layer, the coloration produced tends to bleed by reason of its comparative solubility in the aqueous developing liquid.

It has now been found that a new class of azo coupling components, not heretofore used in diazotype reproduction, can be employed in a light sensitive layer together with a suitable light sensitive diazo compound, or as a developer for a one-component diazotype layer, to form an image in a sepia color of high actinic opacity and good visual density, while at the same time avoiding the difiiculties mentioned above which are encountered by similar use of resorcinol. The class of compounds employed as azo coupling components in accordance with this invention are carbonic ester derivatives of resorcinol which can be prepared by reacting resorcinol with phosgene in the presence of a suitable HCl acceptor or reaction medium, such as pyridine, dimethyl aniline, quinoline or other tertiary nitrogen bases. Prep:- aration of such compounds is disclosed by Einhorn in Liebegs Annalen 300-, page 152.

The reaction of resorcinol with phosgene under the aforesaid conditions apparently results in the formation of carbonic acid ester derivatives of resorcinol of which the exact constitution is: in: doubt, but apparently varying according to the proportions of the inter-reacting reagents from di-resorcyl carbonate (resulting from reaction of 2 moles of resorcinol with 1 mol of phosgene) to polymeric resorcinol carbonates of molecular size which increases as the proportion of phosgene reacting with the-resorcinol approaches an equimolecular amount. The probable general formula for the carbonic ester derivatives of resor cinol ofthis invention is as follows:

wherein n. isan integer of the series of 0,,1,,2, 3 Allof the. compositions or mixtures formed by the aforesaid. reaction can be used as coupling. components. in. diazotype compositions and processes in accordance with this invention.

While it is not. desired to limit the invention to any theory, it is believed that the aforesaid" carbonic ester derivatives of resorcinol, particularly those of relatively complex. structure, are. incapable of coupling per se with light. sensitive diazo components, and hence, when used in atwo-component diazotype layer, the latter is stable-to premature coupling, even upon prolonged storage. However, under the alkaline conditions prevailing during development, the aforesaid resorcinol derivatives are decomposed to form. less complex compounds adapted to couple with the di'azo. component. Regardless of the correctness of this theory, it has been found. that when the resorcinol derivatives of this invention are employed together with alight sensitive diazo compound in a two-component diazotype layer, the. product obtained possesses a high degree of stability against premature coupling, under the usual conditions of temperature. and humidity to which it is subjected during prolonged storage, as well as under accelerated; aging. tests which simulate the effect of. prolonged storage.

Thus, it is possible in accordance with the. invention, to make transition. prints having a colorl'ess background of. excellent actinic transparency l rom two-component diazotype materials which include the resorcinol: derivatives of this invention as coupling components, even after prolonged storage such as may be required for commercial. distribution of the material. In this respect, the resulting transition prints'are vastly superior. to those obtained with diazotype materials containing resorcinol itself as the coupling componenti. The image produced with materials of this invention has equal or better covering power and: opacity toultraviolet light, superior f'ast'nes's to; light and; washing, better visual density, and reatly Improved: resistance: to: ofisetting; as cont-r pared with transition prints produced with resorcinol. The transition prints produced in accordance with the invention are therefore highly advantageous for the production of large numbers oflcopies.

In the preparation of diazotype layers or materials for use in making intermediate or transition copies in accordance with this invention, a transparent. base suchastransparentized paper, a film of transparent plastic material such as regenerated cellulose or an organic derivative of cellulose- (cellulose ethers and esters such as ethyl cellulose. or cellulose acetate) can be used. The base is: coated or impregnated with a sensitizing composition in any manner known to the art, particularly by applying thereto a solution containing the light sensitive diazo compound together with the other ingredients ordinarily used in diazotype sensitizing compositions such as metal salts, stabilizers, anti-oxidants, humectants and the like. The solvent medium employed is preferably compounded to penetrate or impregmate the base material and ordinarily contains asubst'antial proportion of water to insure solution of the sensitizing components therein. In preparing two-component diazotype material in accordance with this invention, a carbonic ester derivative of resorcinol' of the type described above is incorporated in the sensitizing composition, or can be applied separately (e. g., by apply-- ing it in a separate solution or by rubbing it in powdered form on the surface of the carrier);

As light sensitive diazo components, we prefer to use those which are derived from p-diamines of the benzene series, particularly those in which at least one of the hydrogens of one of the amino groups is substituted by such groups as alkyl, alkoxyalkyl, aryl, aralkyl, alkylol', cycloaliphatic and' heterocyclic groups. However, other diazo components have also been found suitable,. such as diazoanhydrides of amino naphthols. These. diazo compounds can be used in: the. form of. stabilized derivatives such as the zinc, cadmium or tin chloride double salts, fluoroborates, or alkyl or'aryl'sulfcnate' complexes.v Examples of amines from which suitable light sensitive dia'zo cone pounds are derived include p-amino-N'--(-2'-hy'- droxyethyl)QT-methyl-amino-benzene, p-aminm diphenylamine, monoethylamino-2'-(or -&'-) methyl 4 arninobenzene, 1 N"- ethyl- N:'-- (2:"-.

hydroxyethyl) -amino-3-methyl-4.-aminobenzene,,

I-N, N-diethylamino-3-ethoxy-4-aminobenzema. l-N-benzoylamino-Z, 5-diethoxy-(cr dimethoxyt- 4-aminobenzene, l-N, N-diethylamin'o-i-amino! benzene, I-N, N-di (2'-hydroxyethyl')'-amino 3=- chlorol-aminobenzene, l-N-benzyl-Nf-ethylanrino-e-aminobenzene, l-N, N dimethylamino-taminobenzene, l-ethylamino-4saminobenzene; 1-.1 N-ethyl N (2 hydroxyethyl') -amino-4-amino benzene, p-phenyiene diamine, l N di(2'. hydroxyethyl)-amino-4-aminobenzene, and 2",. 5-. dlEthOXY-4- (p-ethoxyp-henyl') aniline.

The lightsensitive layers can be sensitized byany of the various methods employed in": diazotype processes. For example, the carbonicv ester'de rivatives of resorcinol' described above can be ap:-.-- plied to the transparent or'semi-transparent base: or carrier in a coating solution, together with a; stabilized diazo compoundi or the aforesaid" coupling components can be robbed on the surface to'be sensitized in powdered form. before or. after application of the. diazo compound. In. a one.- component system, the sensitive layer is formed by applying the. light; sensitive diazo component without the coupling component to: a transparent assumes crorsemietransparentazcarrier"-andcin thisiscasesa couplingn'componentmf th e; describedzpabova and prepared in a'ccordancezi ith .thi'szinvention-iis incor'poratedT: in rthea developing; solutioniwhichrzisi applied totheiidiazotypei-layerz'afterx'exposureit tion-. containings the..following.. ingredients and made up with' watersto a volume offlOI) 00.:

328 g'.'-- of- 'carboni'c estersderivative of: resorcinol,-E

prepared by'reactio'nofchmoloferesorci-nol with:

1 "mol of phosgene v ot N (2" hydroxyethyl)sNemetm lanilineei p-diazo zinc chloride double salti 5' cciethylene glycol tion .was dried and then submitted to anaccelerated aging test, together with a sample of control position, except that it, containedresorcinol in; steadof tl'ie carbonicester derivative ofresorcino l" as the,..azo; coupling component; The sensitized materials were exposed to light under an orig: inal andtfthe. image developed by tr'eatment with ammonia' fumesi. Tli lcop'y. produced from the material sensitized in accordance with the invention yielded a clear:sharpeimage of the original with colorless backgroundareas swhereas the control sample prepared with resorcinol showedconsiderable discoloration in the background areas. Thepatterrrof theoriginal-was reproduced on the material in accordancewith the invention inra da'rkereand less reddishsepia shade1of',"ex' celle'nt visual density which possessed'fgreater opacity. to ultraviolet light, superior fastn'ess; to light andw'a'shing', andgreater resistance to off setting than the-limageobtainedion the resorcinolcontaimng control material..- Further prints. wereobtained on ordinary diazotype photoprinting material'by employing the copies'produced'with the transition printing material of this example as the original, the resulting copies having excellent line density and sharpness, and no background discoloration. 7

Example 2 Transparentized paper was coated with a solution made up with water to a volume of 100 cc., containing the following ingredients:

4 g. of a carbonic ester derivative of resorcinol, prepared by reaction of 2 mols of resorcinol with 1 mol of phosgene 4 g. of N-(2'-hydroxyethyl)-N-methylaniline-pdiazo zinc chloride double salt 5 cc. isopropanol 5 cc. ethylene glycol 8 g. citric acid a g. thiourea 0.5 g. saponin diethylani-line-p-diazo zincachloride; double salt,

materiali'coat'e'd lwitli asimilarl sensitizing coma 63 i Thetrsensitized;.rmaterial;thuszzohtained LWfiSEiJQm SQ ployed in the manner.-described-irrxthe precedi example'sfor. the: preparationoi transitional), irxts. andiilikewise: tested to compare: it;with mater prepared: in .ssimilan manner but; containing res;

sorcinol instead :oftheeaforesaid carbonic; est r: derivativeeoi :resorcinoh .Eiuperior---resultswere obtained similar to;those oirExample' 1;

Example- 3."

lransparentized paperwas coated with 8/501? tion made" up. to a volume of cc. with ,waten: contaimngjthefollowing ingredients? 3:4 g. of-'a carbonic ester derivative oi resorcin'oli prepared by reacting 1 molof'resorcinorwith l molofphosgene 326 gr of"N ethyl aniline-p-diazo zinc' chloride double salt ozs gs-citricacid- 3 cc. phosphoric acid 5'1'0 cc; isopropanol 4.0g; thiourea Uponuse of the resulting sensitizedmaterialfon thepreparation of-transition printsand subse-- quent use of these prints for making. additional.

copies, resultswere obtained showing advantages similar:to' those-.obtained in .the. preceding exe amplesp v similarresults are obtained.when;3,.9 g. Qi NbN- aresubstituted for the N-ethyl-anilineep-diazol compound in the sensitizing-solution ofethis: eX-.. ample.

Exampled Transparentized paper wascoated with a solu-" tion; made up to a'volume of 100' ccrwith water; containing the following ingredients:

4.0 g. of a carbonic ester derivative of resorcinol, prepared :by reacting zmols of resorcinol with l molioiphosgene. 4.0g. N-ethyl m-toluidinerpediazo zinc. chloride;

double. salt.

4 5.0Jcc. .isopropanol 520cc..ethyleneglycoL 8.0' 'g.,citric'acid 410 "g. thiourea.

0.5. .g. ,saponin,,

1 Transition prints "prepared-with; the-:sensitized material" obtainedv on drying were clriaracterized,- lam-advantages and properties similar to thoseof" the: prints obtained inthe preceding. examples.

As indicated the comparative, accelerated agingtests, the diazotype transition'print mate-1- rialsvof '.-.eacid of the foregoing. examples possess; excellent stability against premature coupling during prolonged storage under average atmospheric conditions and are superior in this respect to similar materials in which resorcinol is used as the coupling component.

Instead of developing the images in the foregoing examples by the dry process involving treatment with ammonia vapor, an aqueous alkaline solution such as a solution of an alkali metal carbonate or tertiary phosphate (e. g., a 5-20% aqueous sodium carbonate solution) can be applied in a wet or semi-wet development step to the sensitized materials after they have been exposed to light under an original to be reproduced. The prints prepared in this manner have clear sharply defined images accurately reproducing the original; whereas, when resorcinol is used instead of the carbonic ester derivatives of the invention, the images tend to become blurred 7 by reason of the comparatively water-sensitive nature of the coloration produced.

I One-component diazotype transition print material can be made in the same manner as disclosed in the examples, except that the carbonic ester derivatives of resorcinol are omitted in preparing the sensitizing compositions, and are included instead in an aqueous alkaline developing solution which is applied to the prints after exposure to light in accordance with a predetermined original design or pattern. Such solutions contain for example alkaline reacting salts such as alkali metal carbonates or tertiary phosphates, and the carbonic ester derivative of resorcinol, the latter being employ-ed, for example, in a concentration of l to 10%. The alkaline salts, e. g., sodium carbonate, can be used, for example, in a concentration of to 2G%. As in wet development of two-component systems, sharp images are thus obtained, which are superior in this respect to prints similarly obtained by use of resorcinol as the developer. In other respects, the prints obtained in wet development of oneor two-component layers in accordance with the invention have the same advantages as described in the examples.

Instead of transparentized paper, films, e. g., of regenerated cellulose or of organic derivatives of cellulose, such as cellulose acetate or ethyl cellulose, can be used as the carrier and sensitized with compositions similar to those in the examples. Ordinary paper or other opac ue carriers can be used where transparency is not desired in the copies produced.

Other variations and modifications, which will be obvious to those skilled in the art, can be made in the compositions, materials and processes hereinbefore described, without departing from the scope or nature of the invention.

We claim:

1. In the process of preparing diazotype copies, the step which comprises reacting the residual light sensitive diazo compound contained in a light sensitive diazotype layer after exposure thereof to light in a pre-determined pattern, with a carbonic ester which is a reaction product of 1 mol of phosgene with 1 to 2 mols of resorcinol in the presence of an alkaline reagent.

2. In the process of preparing diazotype transition copies involving exposure or" a transparent carrier, having thereon a sensitized layer containing a light sensitive diazo compound, to light in a pre-determined pattern, the improvement which comprises developing the image thereby formed by reaction of the residual diazo compound with a carbonic ester which is a reaction product of 1 mol of phosgene with 1- to 2 mols of resorcinol in the presence of an alkaline reagent.

3. A light sensitive diazotype layer on a suitable base, containing a light sensitive diazo compound and a carbonic ester which is a reaction product of 1 mol of phosgene with 1 to 2 mols of resorcinol.

4. Diazotype photoprinting material for transition copies comprising a transparent carrier having thereon a light sensitive layer comprising a light sensitive diazo compound and a carbonic ester which is a reaction product of 1 mol of phosgene with l to 2 mols of resorcinol.

5. Diazotype photoprinting material comprising a carrier having thereon a light sensitive layer containing a diazotized p-diamine of the benzene series and a carbonic ester which is a reaction product of 1 mol of phosgene with l to 2 mols o1 resorcinol.

6. Diazotype photoprinting material for transition copies comprising a transparent carrier having thereon a light sensitive layer containing a diazo compound of l-mono-ethylamfno-2-methyle-aminobenzene, and a carbonic ester which is a reaction product of 1 mol of phosgene with l to 2 mols of resorcinol.

"I. Diazotype photoprinting material for transition copies comprising a transparent carrier having thereon a light sensitive layer containing a diazo compound of l-N,N-diethylamino--aminobenzene and a carbonic ester which is a reaction roduct of 1 mol oi phosgene with 1 to 2 mols of resorcinol.

8. Diazotype photoprinting material for transition copies comprising a transparent carrier having thereon a light sensitive layer containing a diazo compound of N 2 hydroxyethyl) N methylamino-p-aminobenzene and a carbonic ester which is a reaction product of 1 mol of phosgene with l to 2 mols of resorcinol.

WILLIAM H. VON GLAHN. LESTER N. STANLEY.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,246,425 von Poser et al Jan. 17, 1941 2,334,495 Kendall Nov. 16, 1943 2,437,868 von Glahn et al. Mar. 16, 1948 FOREIGN PATENTS Number Country Date 836,144. France Oct. 10, 1938 

1. IN THE PROCESS OF PREPARING DIAZOTYPE COPIES, THE STEP WHICH COMPRISES REACTING THE RESIDUAL LIGHT SENSITIVE DIAZO COMPOUND CONTAINED IN A LIGHT SENSITIVE DIAZOTYPE LAYER AFTER EXPOSURE THEREOF TO LIGHT IN A PRE-DETERMINED PATTERN, WITH A CARBONIC ESTER WHICH IS A REACTION PRODUCT OF 1 MOL OF PHOSGENE WITH 1 TO 2 MOLS OF RESORCINOL IN THE PRESENCE OF AN ALKALINE REAGENT. 